View source for Implementation:Langchain ai Langchain Anthropic File Search

{{PageInfo|type=Implementation|title=Langchain_ai_Langchain_Anthropic_File_Search}}
{| class="wikitable" style="float:right; margin-left:1em; width:300px;"
|-
! Knowledge Sources
|
* [https://github.com/langchain-ai/langchain Langchain_ai_Langchain]
|-
! Domains
| [[domain::LLM Framework]], [[domain::Anthropic]], [[domain::Agent Middleware]], [[domain::File Search]]
|-
! Last Updated
| [[last_updated::2026-02-11 00:00 GMT]]
|}

== Overview ==

The <code>file_search.py</code> module provides Glob and Grep search middleware that operates on virtual files stored in LangGraph state, enabling agents to search through files managed by the Anthropic text editor and memory tool middleware.

=== Description ===

This module implements <code>StateFileSearchMiddleware</code>, an <code>AgentMiddleware</code> class that adds two search tools to an agent: <code>glob_search</code> (file pattern matching by path) and <code>grep_search</code> (content search using regular expressions). These tools operate on files stored in the <code>AnthropicToolsState</code> virtual file system, making them complementary to the <code>StateClaudeTextEditorMiddleware</code> and <code>StateClaudeMemoryMiddleware</code>. The module also contains internal helper functions for brace-expansion of glob patterns and include-pattern validation.

=== Usage ===

Import <code>StateFileSearchMiddleware</code> and include it in the middleware list alongside a state-based text editor or memory middleware. The search tools will automatically have access to the virtual files in state.

== Code Reference ==

=== Source Location ===
* '''Repository:''' [https://github.com/langchain-ai/langchain Langchain_ai_Langchain]
* '''File:''' <code>libs/partners/anthropic/langchain_anthropic/middleware/file_search.py</code>
* '''Lines:''' 1-354

=== Signature ===
<syntaxhighlight lang="python">
class StateFileSearchMiddleware(AgentMiddleware):
    state_schema = AnthropicToolsState

    def __init__(self, *, state_key: str = "text_editor_files") -> None: ...
</syntaxhighlight>

=== Import ===
<syntaxhighlight lang="python">
from langchain_anthropic.middleware.file_search import StateFileSearchMiddleware
</syntaxhighlight>

== I/O Contract ==

=== Inputs ===
{| class="wikitable"
|-
! Name !! Type !! Required !! Description
|-
| state_key || str || No || State key to search. Default <code>"text_editor_files"</code>. Use <code>"memory_files"</code> to search memory tool files
|}

=== Tool: glob_search Inputs ===
{| class="wikitable"
|-
! Name !! Type !! Required !! Description
|-
| pattern || str || Yes || The glob pattern to match files against (e.g., <code>**/*.py</code>)
|-
| path || str || No || The directory to search in (default: <code>"/"</code>)
|}

=== Tool: grep_search Inputs ===
{| class="wikitable"
|-
! Name !! Type !! Required !! Description
|-
| pattern || str || Yes || Regular expression pattern to search for in file contents
|-
| path || str || No || The directory to search in (default: <code>"/"</code>)
|-
| include || str or None || No || File pattern filter (e.g., <code>"*.js"</code>, <code>"*.{ts,tsx}"</code>)
|-
| output_mode || Literal || No || Output format: <code>"files_with_matches"</code> (default), <code>"content"</code>, or <code>"count"</code>
|}

=== Outputs ===
{| class="wikitable"
|-
! Name !! Type !! Description
|-
| result || str || Newline-separated search results. Returns <code>"No files found"</code> or <code>"No matches found"</code> if empty
|}

== Key Mechanisms ==

=== Glob Search ===

The glob search uses <code>PurePosixPath.match()</code> to match file paths against glob patterns. It handles the <code>**/</code> prefix specially to also match files in the base directory. Results are sorted by modification time (most recently modified first).

=== Grep Search ===

The grep search compiles the pattern as a Python regular expression and searches line-by-line through file contents. It supports three output modes:

* '''<code>files_with_matches</code>:''' Returns only the file paths containing matches (sorted)
* '''<code>content</code>:''' Returns <code>file:line_number:content</code> format for each matching line
* '''<code>count</code>:''' Returns <code>file:count</code> format showing match counts per file

=== Brace Expansion ===

The internal <code>_expand_include_patterns</code> function handles brace expansion for include filters (e.g., <code>*.{py,pyi}</code> becomes <code>["*.py", "*.pyi"]</code>). This enables users to specify multiple file extensions in a single include pattern.

=== Pattern Validation ===

Include patterns are validated by <code>_is_valid_include_pattern</code>, which:

* Rejects empty patterns
* Rejects patterns containing null bytes, newlines, or carriage returns
* Verifies brace expansion succeeds
* Confirms each expanded pattern compiles to a valid regex via <code>fnmatch.translate</code>

== Usage Examples ==

=== Basic Usage ===
<syntaxhighlight lang="python">
from langchain.agents import create_agent
from langchain_anthropic.middleware.anthropic_tools import (
    StateClaudeTextEditorMiddleware,
)
from langchain_anthropic.middleware.file_search import StateFileSearchMiddleware

agent = create_agent(
    model=model,
    tools=[],
    middleware=[
        StateClaudeTextEditorMiddleware(),
        StateFileSearchMiddleware(),  # Searches text_editor_files by default
    ],
)
</syntaxhighlight>

=== Searching Memory Files ===
<syntaxhighlight lang="python">
from langchain_anthropic.middleware.file_search import StateFileSearchMiddleware

# Search memory tool files instead of text editor files
search_middleware = StateFileSearchMiddleware(state_key="memory_files")
</syntaxhighlight>

== Related Pages ==

* [[Langchain_ai_Langchain_Anthropic_Tools_Middleware|Anthropic Tools Middleware]]
* [[implemented_by::langchain.agents.middleware.types.AgentMiddleware]]
* [[uses_heuristic::PurePosixPath.match for glob patterns, re.compile for grep patterns]]

[[Category:Implementations]]